Some vehicles, in particular single-volume vehicles or an estate car or a station wagon type vehicles include longitudinal bars permanently disposed on top of the roof of the vehicle. They constitute lateral fixing means for a load placed on the roof if the roof is load-supporting.
Such bars also constitute a base for installing transverse bars intended for supporting a load when the roof is not load-supporting.
Such transverse bars are accessories that should be removed when no longer in use. They generate wind noise and they constitute a factor that increases wind resistance, and thus fuel consumption. If not absolutely essential, the removal of such transverse bars is at least advisable and constitutes a constraint on the user since a "home" must be found for the bars when they are not in use. In many cases this "home" is constituted by the luggage compartment of the vehicle, thereby conflicting with intelligent use of the luggage compartment.
One solution, known in particular from document DE-A-3 814 799 consists in providing housings in the longitudinal bars for the transverse bar elements. That solution is quite complex and above all it gives rise to a roof-rack that is heavy. In addition, in an option where the transverse bar elements are to be added, it requires the user to implement an assembly that is somewhat complicated and that uses a hinge.